Drilling directional and/or horizontal wells requires the use of a survey tool, referred to as a steering tool, to monitor the well bore path. One method of transmitting the survey information required to measure the orientation of the drill bit and well bore path is by the use of an electrical conductor connected between the steering tool and the well surface for conducting signals.
Horizontal or high angle well bores, unlike conventional vertical well bores, are used to drill long well bore intervals in the target pay zone. As a result, many horizontal wells are drilled live (producing oil/gas) which requires the use of blowout control equipment at the well surface and around the outside of the drill string. This requires that the electrical conductor conducting signals from the steering tool to the well surface be inside of the drill string.
In directional and/or horizontal drilling, steerable drilling motors or rotary drilling assemblies are used to drive a drill bit to drill a controlled well path. This technology requires a combination of drill string rotation and slide drilling to control the direction and inclination of the drill path. Conventional wireline steering techniques prevent drill string rotation while the steering tool is downhole and connected through an electrical conductor to the well surface. Pulling the electrical conductor and/or steering tool for string rotation is not always economical or achievable in high angle and horizontal drilling due to seating problems. These problems are further magnified as the wireline electrical conductor from the well surface to the steering tool must be lengthened or shortened as additional pipe joints are added to or subtracted from the drill string as drilling continues. This creates additional problems of support of the electrical conductor in deep wells.
The present invention is directed to the use of a wireline electrical conductor method and apparatus for connection to a steering tool used to monitor tool face orientation and to survey the well path in directional and/or horizontally drilled wells. The present invention allows better control of the well while drilling, especially during live drilling, as the wireline electrical conductor will be totally inside the drill string. In addition, drill string rotation for steerable drilling assemblies is not hampered by the wireline electrical conductor due to its construction and operation. Furthermore, the wireline conductor may be quickly positioned so as not to interfere with the addition to or the substraction of pipe joints to the drill string.